Cow's milk is comprised of water, fats, carbohydrates, proteins, vitamins, minerals and enzymes. The majority of milk, 87 percent, is water. The carbohydrates of milk are present in the form of lactose, comprising 4.9 percent of the product.
The fat content of milk varies significantly based on the animal the milk comes from and post-product fat reduction. Fat-free bovine milk has the lowest fat content, with 0.20 grams per 8-ounce serving. Full-fat water buffalo milk, at the other end of the spectrum, has 16.81 grams of fat per serving.
The protein content of milk comprises roughly 3.3 percent of the product. The protein of milk comes in two forms, casein and whey; the former is found at 82 percent while the latter at 18 percent.
The vitamins A, B1, B2, B3, B5, B6, B12, C, D, E and K, as well as folate are found in varying quantities in milk. Minerals, such as calcium, copper, iron, magnesium, manganese, phosphorous, potassium, selenium, sodium and zinc, are also present.